Technical Field
Embodiments of the subject matter disclosed herein relate to exhaust gas recirculation (EGR) systems and methods.
Discussion of Art
Some engines utilize recirculation of exhaust gas from an engine exhaust system to an engine intake system, a process referred to as exhaust gas recirculation (EGR), to reduce combustion temperatures and regulated emissions. In some examples, a first group of one or more cylinders provides exhaust gas that is directed through an EGR passage coupled between the first group of cylinders and an intake manifold to provide EGR while a second group of one or more cylinders provides substantially no exhaust gas to the EGR passage. In such a configuration, EGR rate is typically controlled through operation of a valve that is located in the EGR passage. The valve position is controlled to vary a mass flow rate of EGR provided to the intake manifold. However, a relatively large amount of latency exists in the EGR system, making it difficult to deliver a desired amount of EGR during changing engine operating conditions.